This invention relates to a mixture of phenylindane diamines as a new composition of matter.
In an article by J. C. Petropoulos and J. J. Fisher, J. Amer. Chem. Soc., 80, 1938 (1957) concerned with the dimerization of .alpha.-methylstyrene derivatives, there is reported the dinitration of ##SPC1##
To yield 1,3,3-trimethyl-6-nitro-1-(4'-nitrophenyl)-indane in low yield. In this article there is also reported the reduction of the above pure dinitro compound to the pure diamine, 1-4'-aminophenyl)-1,3,3-trimethyl-6-aminoindane. The preparation of the above 6-nitro and 6-amino compounds is also described in U.S. Pat. No. 2,855,420. The 6-amino diamine derivative is used in U.S. Pat. No. 2,855,420 to prepare a diisocyanate and a diisothiocyanate.
It has now been discovered that a particularly useful mixture of diamines may be obtained by first preparing, through acid-catalyzed dimerization of .alpha.-methylstyrene, 1,3,3-trimethyl-1-phenylindane, and by then simply nitrating and reducing this phenylindane. In this process, the total reaction product after nitration of the above phenylindane is reduced, without any separation of specific dinitro isomers. Thus, the phenylindane diamine mixture of the present invention is produced through a much simpler procedure than that described in the above-mentioned prior art, thereby effecting a significant economy. Furthermore, the phenylindane diamine mixture so obtained has a number of exceptional properties which are unexpected in view of the prior art. For example, polymers derived from this phenylindane diamine mixture such as polyimides, polyamide-imides and polyamides, show exceptional solubility characteristics and exceptional thermal characteristics, such as high glass transition temperatures (Tg's). Furthermore, the phenylindane diamine mixture is low melting and yet epoxy resins cured by it show even higher Tg's than products cured by conventional, higher melting aromatic curing agents. This lower melting permits a much simplified casting procedure to be used in an epoxy resin/aromatic amine system.